Goodman GDS80804 air flow direction

MaxMercy

Hi, I bought a commercial building that has a fairly new Goodman GDS80804 gas furnace that was apparently installed to replace an earlier unit as the duct work is far older. The problem is that the furnace pulls the air from the output registers and blows it out the input where the filter is cut in.

Is there a way to reverse the airflow by changing the motor and fan, or is there more to it. From the outside, this downflow furnace looks like the upflow model that should have been installed, but they have different part numbers.

Any insight greatly appreciated.

STEVEusaPA

Maybe the blower was replaced and the dunce didn't check/change the rotation. Or they put the filter on the supply instead of the return...less likely.
First confirm which way the air is supposed to flow. If it is backwards, it might be as simple as changing the blower motor rotation, or getting the right motor.

Jamie Hall

Generally you can't just change the direction of rotation -- the blower has to be changed as well, and depending on exactly how the system is set up that may not work, either.

MaxMercy

STEVEusaPA said:

First confirm which way the air is supposed to flow. If it is backwards, it might be as simple as changing the blower motor rotation, or getting the right motor.

The model number indicates it's a dedicated downdraft furnace. Unfortunately, the ductwork is currently on top of the furnace, so it's sucking air backwards and blowing *out* the filter..

Fortunately, it's a commercial building and the furnace is otherwise working properly so there's no chance of freeze up, but I have to get this figured out.

Jamie Hall said:

Generally you can't just change the direction of rotation -- the blower has to be changed as well, and depending on exactly how the system is set up that may not work, either.

I'm hoping a motor and blower wheel will do the job, but I'm not sure of the internal makeup of the cabinet. I guess what I need are service manuals for both.

Thanks for the input guys.

EdTheHeaterMan

@MaxMercy, you have the wrong furnace. Nothing you can do to change the direction of flow. If you remove the blower and somehow get the fan reinstalled to blow the opposite direction, you will be pulling the hottest air in the system over the fan motor and any controls that are in the blower compartment. you will be replacing circuit boards and blower motors 2 and 3 times a season. That is why the fan is always on the return of a furnace, and the heat source is always on the discharge side of the fan.

Someone who was inexperienced did a DYI with a furnace that they got from a guy who knew a guy... if you know what I mean

EBEBRATT-Ed

Think @EdTheHeaterMan is correct

Jamie Hall

So do I...

MaxMercy

EdTheHeaterMan said:

@MaxMercy, you have the wrong furnace. Nothing you can do to change the direction of flow. If you remove the blower and somehow get the fan reinstalled to blow the opposite direction, you will be pulling the hottest air in the system over the fan motor and any controls that are in the blower compartment. you will be replacing circuit boards and blower motors 2 and 3 times a season. That is why the fan is always on the return of a furnace, and the heat source is always on the discharge side of the fan.

Yeah, that makes sense. The only good thing is that a new one with the right flow direction is the same exact cabinet dimensions so there won't be really any installation to deal with. A friend of mine can do the gas hookup.

Thanks.

mattmia2

so someone still makes a furnace that can't be reconfigured for different orientations?

SuperTech

Most furnaces can be installed vertically or horizontal left or right.  I've never seen one that can be reconfigured from upflow to downflow. Downflow furnaces are a different design usually. 

HVACNUT

A down flow furnace has safeties and limits in different locations. If its moving the air its designed to move, then you can just leave it. Or install an up flow. It would drive me absolutely bonkers if I had to look at it every day. 

MaxMercy

I'm going to investigate whether I can move the furnace back a bit and just reconfigure the ductwork. If not, I'll just order a new furnace and have it installed.

Thanks again everyone.

unclejohn

@mattmia2 Most furnaces you or I would get are multi position but I think Lennox and Goodman apparently still make a downflow only. This model by Goodman however has been discontinued.